Fuel Pump Electrical Circuit Diagnosis

FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS - FUEL PUMP ELECTRICAL DIAGNOSIS

CIRCUIT DESCRIPTION
When the ignition is turned ON, the powertrain control module (PCM) turns ON the fuel pump relay, which turns ON the in-tank fuel pump. The in-tank fuel pump remains ON as long as the engine is cranking or running and the PCM is receiving reference pulses. If there are no reference pulses, the PCM turns the in-tank fuel pump OFF 2 seconds after the ignition is turned ON or 2 seconds after the PCM no longer receives reference pulses.

DIAGNOSTIC AIDS
- Inspect the ground connection for the fuel pump. Ensure all ground connections are clean and tight.
- The following conditions may have caused the fuel pump fuse to open:
- The fuse is faulty.
- There is an intermittent short in the fuel pump power feed circuit.
- The fuel pump has an intermittent internal problem.
- For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections. Component Tests and General Diagnostics

TEST DESCRIPTION

Step 1 - Step 13:

Step 14 - Step 25:

Step 26 - Step 27:

The numbers below refer to the step numbers on the diagnostic table.
3. This step determines if the condition is located on the coil side or the switch side of the circuit.
4. This step verifies that the PCM is providing voltage to the fuel pump relay.
5. This step tests for an open in the ground circuit to the fuel pump relay.
6. This step determines if a voltage is constantly being applied to the fuel pump relay.
13. This step determines if the condition with the circuit is intermittent. If the fuse does not open, inspect the supply voltage circuit between the fuse and the fuel pump for an intermittent condition.